       Re: Using "Sum" (i = 1 ... N) in a function definition

• To: mathgroup at smc.vnet.net
• Subject: [mg49709] Re: [mg49666] Using "Sum" (i = 1 ... N) in a function definition
• From: Murray Eisenberg <murray at math.umass.edu>
• Date: Thu, 29 Jul 2004 07:43:26 -0400 (EDT)
• Organization: Mathematics & Statistics, Univ. of Mass./Amherst
• References: <200407271100.HAA11129@smc.vnet.net>
• Sender: owner-wri-mathgroup at wolfram.com

```MyFunc[i_] := Fold[Plus, 0, Take[MyData, i]]

Rainer wrote:

> I was trying to define a function using the Sum command in the
> following way (simplified example):
>
>  MyData = {3,2,4,5,6};
>  MyFunc[i_] = Sum[MyData[[j]],{j,1,i}];
>
> As you can see, the idea is to use the length of the list (i)
> as a variable in the function definition, such that
>
>  MyFunc = 3
>  MyFunc = 3 + 2 = 5
>  MyFunc = 3 + 2 + 4 = 9
>
> etc. Mathematica does not like the abobe statements, and prints the
> following error message:
>
> "Part specification K\$394 is neither an integer nor a list of
> integers."
>
> Does anybody know how to define (correctly) such a function. Should be
> possible ...?
> Thanks
> Rainer
>
>

--
Murray Eisenberg                     murray at math.umass.edu
Mathematics & Statistics Dept.
Lederle Graduate Research Tower      phone 413 549-1020 (H)
University of Massachusetts                413 545-2859 (W)
710 North Pleasant Street            fax   413 545-1801
Amherst, MA 01003-9305

```

• Prev by Date: Re: Combinations
• Next by Date: Re: Using "Sum" (i = 1 ... N) in a function definition
• Previous by thread: Re: Using "Sum" (i = 1 ... N) in a function definition
• Next by thread: Re: Using "Sum" (i = 1 ... N) in a function definition